greissinger



Feb. 9, 1960 5. GREISSINGER ARTIFICIAL FOOT PROVIDED WITH ANKLE- JOINT Filed July 23, 1957 fr men/5y:

nit tat ARTIFICIAL FOOT PROVIDED WITH ANKLE-JOINT Georg Greissinger, Stuttgart-Vaihingen, Germany Application July 23, 1957, Serial No. 673,659

5 Claims. (Cl. 3-33) This invention pertains to an artificial foot provided with ankle-joint and relates more particularly to an arrangement as described in the USA. Patent 2,620,485 in which the ankle-joint is provided with joint-parts rigidly secured in the foot-part and shank-part, and in which the foot-part and shank-part are provided with cooperating, curved roll-off surfaces of which either one or both consist of elastic material. This known ankle-joint was devised as universal joint or as ball-and-socket joint and for that reason unyielding in longitudinal direction of the leg.

To still further improve the aforesaid ankle-joint, which is of remarkably simple construction and which has been found to permit a perfect gait, is the object of this invention. For this purpose the present invention provides the ankle-joint with an intermediate member which at least partly embraces the pivot bolt and which consists of tenacious, elastic artificial material. This intermediate member forms a part of one of the joint-parts and is provided with a saddle-like recess by means of which it embraces the pivot bolt rigidly secured in the second joint-part from the side facing that second joint-part in U-shaped fashion and practically without lateral play.

This novel type of joint affords to the artificial leg not only an elastic yielding capacity in longitudinal direction of the leg (as the pivot is rigidly secured only to one of the joint-parts, but elastically yieldingly secured to the other joint-part owing to the elastic structure of the latter and owing to the elastic yielding capacity of the roll-off surfaces), but also aifords an automatic compensation for the wear-off occurring at the roll-off surfaces. It permits, furthermore, a certain horizontal turningand lateralswinging capacity of the ankle-joint, so that the universal joint can be dispensed with, and it also enables a soft, elastic gait and also a soft, elastic rolling-off of the footpart. In addition to these advantages the joint of the 5 invention works perfectly noiselessly and has a prolonged life-time. It also is much lighter in weight. The proposed manufacture of the intermediate part from tenacious, elastic artificial material is necessary because the intermediate part must, on the one hand, not be so soft as the elastic roll-off surfaces adjacent the joint, but, on the other hand, has to be hard enough without being brittle, as it has to constitute a firm and reliable connection between the shank-part and the foot-part, and as it has to be abrasion-proof as much as possible.

It should further be mentioned that a joint of this kind does not require any greasing.

Additional features and advantages of the invention will be understood from a consideration of the following detaiied description taken in connection with the accompanying drawings forming a part of this specification and in which an embodiment of the invention has been shown by way of example. However, I wish to say that the invention is not confined to any striot conformity with the showing of the drawings but may be changed or modified, so long as such changes or modifications mark no 2,923,948 Patented Feb. 9, 1960 material departure from the salient features of the invention as expressed in the appending claims.

In the drawings, in which like parts are referred to by the same reference characters,

Fig. 1 is a longitudinal sectional 'view of the artificial foot; I

Fig. 2 is a top plan view of the foot-part;

Fig. 3 is a cross-section on line III-III of Fig. 1;

Fig. 4 is a front view of the joint;

Fig. 5 is a side view of the joint of Fig. 4;

Fig. 6 is a top plan view of the joint of Fig. 4.

The foot-part a, shaped in customary manner, is provided with an elastic member at seated in a suitable recess of the foot-part a. The elastic member at has a curved roll-off surface e, 7 which is adapted for rolling off on the likewise curved counter-surface g, h at the lower end of the shank-part b, whereby the counter-surface g, It may be likewise provided with a recess and with an elastic member seated therein, similar to that of the member d.

The foot-part a and the shank-pant b are movably secured to each other by means of a joint consisting of a lower fork-shaped joint-part t and of an upper joint-part r, s consisting of an intermediate part r and twofastening screws .3.

The lower fork-shaped joint-part t, in whose fork-arms the pivot c is rigidly secured, extends with its threaded shaft k through the foot-part a and is tightly secured within the foot-part a by means of the nut I. In order to prevent the joint-part r from getting rotationally displaced within the foot-part a, the latter is provided with one or a plurality of recesses for the engagement therein of the projecting portions y provided at the fork-shaped joint-part r.

The intermediate part r of the upper joint-part r, s is substantially oblong in shape and is secured in an oblong recess u of the shank-part b by means of screws s extending through bores in the intermediate part r. In the assembled joint structure the intermediate part r is located between the pivot c and the base of the recess in the forkshapecl part 1 (see Figs. 3 and 4). In the middle of its upper surface between the screws s the intermediate part r is provided with a saddle-like recess which embraces the pivot c in U-shaped form from below practically without lateral play and which guides the movements of the two joint-parts with respect to each other. The intermediate part r is produced from a comparatively hard, and yet elastic and tenacious material, which properties are found in certain artificial substances, for example in netted polyurethanes known as vulcolla'n, so that the intermediate part r is enabled to elastically yield within certain limits during the relative movements of the two joint-parts, and yet guarantees a wear-resisting connection of the two joint-parts. Interposed between the heads of the screws s and the lower surface of the part r facing the screw-heads is a washer v consisting preferably of metal. As the wood of the shank-part b does not offer a sufiicient degree of resistance for the screws s to be securely seated in, there has been inserted into a bore of the shank-part b from the side of the latter a fiat bar w provided with a pair of threaded bores through which the screws s are screwed and in which they are securely anchored with their threaded shafts.

In order to secure for the joint-parts with simplest means the necessary degree of play the bottom surface of the recess u in the shank-part b has been provided with a recessed portion extending parallel to the pivot c (not shown in the drawings). In addition to this, a similar recess of the saddle-like recess of the intermediate part r may be provided oppositely in the other front face of the intermediate part r. This latter recess need not extend over the entire width of the intermediate part.

The joint described in the present invention works in such manner that the foot-part a is freely rotatable about the pivot c, while rotary movements about the axis of the leg or tilting movements in transverse direction are opposed by the elastic resistance of the intermediate part r. Stress exerted in the direction of the axis of theleg is softly and elastically absorbed by the roll-ofi-surfaces e, f and g, 11!.

Under certain circumstances it may be possible to substitu'te for the saddle-like recess of the intermediate part r a bore which on all sides embraces the pivot 0. Also the manner offastening the elastic intermediate part and the joint partsat the appertaining foot-part and shankpart may be changed.

What I claim as new and desire to secure by Letters Patent of the United States is:

-l. Artificial foot, comprising a foot-part provided with a substantially annular transversely curved roll-off portion; a shank-part provided with a roll-oft portion, said roll-ofi portions of said foot-part and said shank-part being of curved 'formation and suitably positioned and adapted for cooperation with each other, and at least one of said roll-off portions being of elastic material; and an ankle-joint consisting of two joint-parts adapted for cooperation with each other, both of said joint parts being substantially of U-shape, one of said joint-parts being rigidly secured in said foot-part, and a horizontally extending pivot bolt being the cross-piece of said U-shape of said foot-part joint-part, the other one of said jointparts being rigidly secured in said shank-part and having across-piece of U-shape of tough elastic artificial material, both of said cross-pieces engaging one another and being in direct contact.

2. Artificial foot-in accordance with claim 1, in which said cross-piece of said shank-part joint-part is provided with-"a saddle-like recess; and in which said pivot bolt is rigidly secured in said joint-part rigidly secured in said foot-part and snugly embraced from below by said saddlelikerecess of said cross-piece of said shank-part jointpart.

3.'Artificial foot in accordance with claim 1, in which said cross-piece of said shank-part joint-part is directly secured to the joint-part rigidly secured in the shank-part.

4. Artificial foot comprising a foot-part provided with a roll-ofi portion; a shank-part provided with a roll-oil portion, said roll-off portions of said foot-part and said shank-part being of curved formation and suitably positioned and adapted for cooperation with each other, and at least one of said roll-ofi portions being of elastic material; and an ankle-joint consisting of two joint-parts adapted for cooperation with each other, one of said jointparts being rigidly secured in said foot-part and provided with a horizontally extending pivot bolt, and the other one of said joint-parts being rigidly secured in said shankpart and provided with an intermediate part consisting of tenacious, elastic artificial material and with means at said intermediate part adapted to snugly but rotatably embrace at least partly said pivot bolt, and in which the joint-part secured in the foot-part is of fork-shaped formation and provided with projecting portions; and in which the foot-part is provided with recesses adapted for said projecting portions to engage in and to be thereby prevented from rotational displacement within the footpart.

5. Artificial foot comprising a foot-part provided with a roll-off portion; a shank-part provided with a roll-oil portion, said roll-off portions of said foot-part and said shank-part being of curved formation and suitably positioned and adapted for cooperation with each other, and at least one of said roll-oil portions being of elastic material; and an ankle-joint consisting of two joint-parts adapted for cooperation with each other, one of said jointparts beingrigidly secured in said foot-part and provided with a horizontally extending pivot bolt, and the other one of said joint-parts being rigidly secured in said shank-part and provided with an intermediate part consisting of tenacious, elastic artificial material and with means at,said intermediate part adapted to snugly but rotatably embrace at least partly said pivot bolt, and in which said intermediate part is provided with a saddlelikerecess and with a pair of bores vertically extending to said saddle-like recess on both sides of the latter; and in which said shank-part is provided in its interior above said intermediate part with a bar-shaped metal member and with a-pair of threaded bores in said bar-shaped metal member; and in which said intermediate part is secured in its position and against rotational displacement by a pair of threaded bolts extending through said vertically extending bores in said intermediate part and through said threaded bores in said bar-shaped metal member.

References Cited in the file of this patent UNITED STATES PATENTS 2,066,599 Willett Jan. 5, 1937 FOREIGN PATENTS 1,010,648 France Mar. 26, 1952 viii-".1 

